1. Field of the Invention
The present invention relates to a system and method for controlling actuator position, and more particularly to an adaptive system and method that includes error correction.
2. Description of the Related Art
Fluid actuators are used in various hydraulic applications, including skid steer loaders, boom lifts, and mini excavators. The fluid actuators in these applications typically have a piston, which is encased by a cylinder, and a rod, which is attached to some accessory such as a bucket or a boom. In adjusting the position of the actuator, typically an operator of the application must manually actuate a joystick, which controls the position of the fluid actuator, and approximate the position of the actuator based on sight. If the operator's approximation is not correct, the operator must make minor adjustments to the position of the cylinder through the joystick. In some situations, the accurate positioning of the actuator could be critical, such as when positioning an actuator near electrical lines or near gas lines or water mains.
Some manufacturers have recommended using position sensors on the actuators. These position sensors typically require some type of marking on the rod so that the sensor can accurately sense the position of the actuator. While this would likely work in most applications, the sensors and the required markings on the rod significantly affect the cost of the actuator. As a result, most of the fluid actuators on these types of hydraulic applications do not use position sensors.
Information relevant to attempts to address the cost prohibitiveness of position sensing can be found in U.S. Pat. Nos. 6,848,323 and 7,114,430. However, each one of these references suffers from the disadvantage of not being precise enough to provide an accurate location of the actuator.